This invention relates to food, and more particularly to textured protein that is useful in formulating fabricated foods for human and animal consumption.
Protein deficiency is common throughout many parts of the world, with protein malnutrition being the most wide spread and serious nutritional problem in the underdeveloped areas of the world. Rapidly increasing population of the world is further worsening the shortage of protein supply. It is, therefore, necessary to utilize the available protein supply in a manner that is most efficient. High quality meat is one of the most popular sources of diet protein, and the American population has developed taste for the texture, flavor and mouthfeel of meat products. However, present economic conditions have led to scarcity of high quality meat products necessitating the development of meat analogs from more readily available components that are less expensive. Furthermore, the presence of cholesterol and highly saturated fats in meat limit their intake by people with certain health problems such as atherosclerosis. Another sector of world population does not consume meats due to religious or personal beliefs. Therefore, a need exists for the development of palatable, high-quality protein foods from new and more readily available secondary protein sources. There are many sources of secondary protein available. Besides high quality meat, other animal proteins are lower quality meat, poultry, fish, eggs, milk and milk products. Soybeans, peanuts, cereals and other plant or vegetable proteins are the other major secondary protein sources. However, many of these plant proteins and animal protein lack the required palatability and appearance to make them suitable for use. Various methods of modification of these protein sources are being used to make them more palatable both from taste and visual standpoints and therefore, more acceptable. Processes also have been developed to utilize animal and plant proteins in fabricating foods similar in appearance, texture, flavor and taste to the natural foods already accepted.
By high quality meat is meant the customary parts of slaughtered animals ordinarily sold for human consumption. By low quality meat is meant the edible parts of slaughtered animal suitable for human consumption but unacceptable to humans from an aesthetic or appearance point of view. If this low quality meat and other referenced animal protein are modified to have the appearance of high quality meat, an additional source of acceptable protein is provided.
By milk products is meant those protein containing products derived from milk. For example, casein and casein salts are protein products derived from milk. Typical edible casein salts include sodium caseinate, calcium caseinate, ammonium caseinate, magnesium caseinate and other edible casein salts. Modified milk products having the characteristics of high quality meat are also more acceptable than the milk product.
One such modification process for making meat analogs is basically known as texturization of proteins. There are three basic processes for forming texturized proteins. There is a spinning process, an extrusion process, and a glass-puffing extrusion process. The spinning process involves extruding a protein dope or solution through a die into a coagulation bath to form fibers. The problem becomes obvious during the extrusion of the dope and the determination of a proper coagulation bath. In the extrusion process, high pressures and temperatures are used to form a plexilaminate. In this product the cells of the product are longer in the direction of the extrusion. The glass-puffing process is also a high pressure and high temperature process. The use of high pressure and high temperature requires sophisticated, expensive equipment, capital, and skills to handle. The high temperature and pressure also damages the protein thus processed. Furthermore, the protein thus being processed still retains some of its undesirable flavor and taste characteristics. For example, the taste of the protein has not been improved. The type of protein being processed may well not have the desired palatability or aesthetic acceptability. Thus, while there exist processes for forming suitable texturized proteins, many problems still remain to be solved in producing acceptable protein substitutes for meat.
Another problem is that the secondary protein source individually may lack the required nutritional completeness customarily considered acceptable for a protein source. A possible solution to point toward nutritional completeness is combining at least two secondary proteins in one product. The process of combining two or more secondary proteins to form a meat analog suffers from the same difficulties as forming a meat analog from a single protein source.
In the prior art spun protein processes, there is an effluent disposal problem. This effluent results from the basic nature of prior art wet processes. In order to treat the raw protein, the raw material is dissolved in an alkali medium. For example, soy protein isolate can be dissolved in sodium hydroxide solution to form a protein dope. This solution of protein is then extruded into an acid coagulation bath. This acid bath coagulates the protein, and the protein fibers are formed. The fibers thus formed are tender and must be hardened in a salt solution bath to make them suitable for use. Thus, there are three basic steps in the prior art for forming spun protein fibers. In each of the three basic steps a liquid residue is left after the process is complete. It becomes a problem to dispose of these residues.
Recent developments in protein texturization which avoid some problems in protein texturization include the sheeting and film forming technologies. These technologies, however, require forming and partial drying of a particular product before that product can be shaped and texturized. In addition, the textured product loses its shape and identity upon cooking unless pretreated with denaturing agents such as acids and salts. The liquid residues left in the denaturing or fixing process are similar to those in the spinning process and aggravate the waste disposal problem.
Therefore, it is desirable to develop a process for protein texturization that is simple, inexpensive, with minimum waste disposal problems, and having no adverse effect on the nutrition and flavor of the protein being texturized.